This invention relates to towrope systems for towing water-skiers behind a boat and, more particularly, relates to a tow system that provides a monitor of the skier's position and a warning to the towboat operator if the skier should fall into the water. In a preferred embodiment, the system also provides a readout of the length of rope trailing the boat and allows adjustment of the rope length.
Water-skiing has become a popular pastime for many people and this has led to certain areas becoming very crowded with boats and skiers being towed behind boats. Almost inevitably, every skier at one time or another will fall in the water or release the towrope and sink into the water for one reason or another. Sometimes the rope is accidentally released by the skier; sometimes the rope is yanked from the skier's hand when the skier falters. Since the boat operator must focus his attention on the boat operation in order to avoid hitting other boats and skiers or obstacles, it is difficult for the driver to maintain constant watch on the skier to know exactly if and when a skier releases the rope or falls in the water. While a skier towed behind a boat is, in most cases, easily visible to other boats so that collisions between boats and skiers can be avoided, it is a different matter when the skier falls into the water. The skier then is very difficult to see and, in a crowded water area, the chances of a downed skier being struck by another boat are high. The possibility of serious injury to a downed skier has led most states to require a spotter in the towboat to keep constant watch on the skier. The chances of the skier being hit by another boat are diminished if the skier's own boat operator, immediately upon knowing that the skier has fallen, can double back to where the skier is in the water and eithe pick the skier up in the boat or return the towrope to the skier so that he can be again pulled up into a skiing position. The length of time between the time when the skier goes down and the time that he is located and picked up by the towboat or returned to a skiing position is directly proportional to the time it takes the boat operator to realize the skier has fallen. Therefore, it is advantageous for the boat operator to know immediately that the skier has fallen or released the towrope. Also, since the skier is as hard to see for his own towboat as he is for other boats, when he is down in the water, it would be advantageous for the towboat operator to know the approximate location, with respect to the boat, that the skier was in at the time he released the rope so that the towboat operator would have an approximation of the skier's position in the water, even before the skier was sighted by the boat operator.
Attempts have been made to produce warning devices that signal the fall of a water-skier. One of these is shown in U.S. Pat. No. 3,602,188 and operates on the principle of a mechanism that senses the release of tension in the towrope as an indication that the skier has fallen. While this warning system works on most occasions, it also has drawbacks in that it operates solely on the principle that a skier holding onto the line will cause a tension in the line and that the tension will be released only upon the release of the towrope by the skier. In actual water-skiing practice, particularly in slalom skiing, there are times when the rope will go slack, due to change in direction of the skier or the boat and, therefore, there will be a release of tension in the line even though the skier is still upright on the ski(s) and the tension release is only momentary. In such a situation, it is possible for some of the prior art warning systems to operate indicating that the skier has fallen when, in fact, it was merely a short-term slack in the line that was detected, rather than the actual fall of the skier. The prior art systems also do not provide for automatic play-out or reel-in of the towrope, or a communication ability between a skier and the towboat.
It is therefore advantageous to provide a warning device to the operator of a boat towing a skier that indicates to the operator that the skier has fallen or released the towrope for some reason. It is also advantageous for the boat operator to know the approximate angular position of the skier with respect to the boat at the time the towrope was released to aid the operator in finding the downed skier. It is desirable that the warning to the boat operator be related directly to the grip of the skier on the towrope and independent of the tension on the rope so that momentary slack in the line will not be misdiagnosed as a fall.